The Changes of Serum Metabolites in Diabetic GK Rats after Ileal Transposition Surgery

Ileal transposition (IT) surgery could improve metabolism. Metabolomics has been applied comprehensively in analyzing the global dynamic alterations of metabolites. In the present study, we aimed to investigate serum metabolite alterations in diabetic Goto-Kakizaki (GK) rats after IT surgery.

Male GK rats were subjected to IT and Sham-IT surgery. Six weeks later, body weight, food intake, fat mass, and serum biochemical parameters were measured. The serum metabolomic fingerprint was analyzed using ultra-performance liquid chromatography-mass spectrometry (LC-MS)-based, non-targeted metabolomic approach. The differential metabolites were identified using principal component analysis and orthogonal partial least squares discriminant analysis. Metabolic pathway analysis was performed using HMDB and KEGG databases.

The body weight, food intake, fat mass, serum levels of glucose and insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) of IT rats were significantly decreased when compared with Sham-IT rats (all P < 0.05). In the metabolomics analysis, ten serum differential metabolites were identified. Compared with Sham-IT rats, serum LysoPC(O-18:0) and PG(20:4/20:0) of IT rats were decreased, while genistein 4'-O-glucuronide, 5,6:8,9-Diepoxyergost-22-ene-3,7beta-diol, PI(16:0/18:2(9Z,12Z)), docosapentaenoic acid, 3-Oxo-4,6-choladienoic acid, 3-Oxocholic acid, and TG were increased. Pathway analysis highlighted the following pathways: ether lipid metabolism, alpha linolenic acid and linolenic acid metabolism, incretin synthesis and secretion, free fatty acid receptors, and biosynthesis of unsaturated fatty acids.

IT surgery could significantly decrease body weight and fat mass and improve glucose metabolism in diabetic GK rats. These beneficial effects might be related to the changes of serum metabolites which involved in lipid metabolism, bile acids, and incretin.